CVE-2009-2055

Exp

Cisco IOS XR 3.4.0 through 3.8.1 allows remote attackers to cause a denial of service (session reset) via a BGP UPDATE message with an invalid attribute, as demonstrated in the wild on 17 August 2009.

Published: 2009-08-19 Last update: 2026-04-22 Assigner: [email protected] Source: [email protected]

NVD Status：Analyzed，CVE State: published

View at NVD, CVE.org, EUVD

Threat Intelligence & Risk Assessment for CVE-2009-2055

KEV EPSS CVSS CWE Affected

Conclusion & alert: CVE-2009-2055 is rated Active Exploitation (74.7/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.77%). Core evidence: CISA KEV confirms active exploitation (added 2022-03-25) affecting Cisco / IOS XR. a weakness (CWE-20) Unauthenticated remote administrative access may be possible. Mandatory action: The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2009-2055

Name: Cisco IOS XR Border Gateway Protocol (BGP) Denial-of-Service Vulnerability · CISA KEV detail

Exploit added: 2022-03-25

Action due: 2022-04-15

Required action: Apply updates per vendor instructions.

Exploit prediction scoring system (EPSS) score for CVE-2009-2055

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-23	0.41%	0.77%	+0.36%
2	2026-02-22	0.61%	0.41%	-0.20%
3	2026-01-13	—	0.61%	—

Full EPSS history (17 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2009-2055

CVSS metrics for this CVE.

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.9	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.2	3.6	134c704f-9b21-4f2e-91b3-4a467353bcc0
4.3	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:N/I:N/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:P) Partial availability impact.	8.6	2.9	[email protected]

Weakness enumeration for CVE-2009-2055

CWE-20 MITRE ↗

Affected software / configurations for CVE-2009-2055

Vendor	Product	Version	Raw CPE
cisco	ios_xr	3.4	cpe:2.3:o:cisco:ios_xr:3.4:::::::*
cisco	ios_xr	3.4.0	cpe:2.3:o:cisco:ios_xr:3.4.0:::::::*
cisco	ios_xr	3.4.1	cpe:2.3:o:cisco:ios_xr:3.4.1:::::::*
cisco	ios_xr	3.4.2	cpe:2.3:o:cisco:ios_xr:3.4.2:::::::*
cisco	ios_xr	3.4.3	cpe:2.3:o:cisco:ios_xr:3.4.3:::::::*
cisco	ios_xr	3.5	cpe:2.3:o:cisco:ios_xr:3.5:::::::*
cisco	ios_xr	3.5.2	cpe:2.3:o:cisco:ios_xr:3.5.2:::::::*
cisco	ios_xr	3.5.3	cpe:2.3:o:cisco:ios_xr:3.5.3:::::::*
cisco	ios_xr	3.5.4	cpe:2.3:o:cisco:ios_xr:3.5.4:::::::*
cisco	ios_xr	3.6.0	cpe:2.3:o:cisco:ios_xr:3.6.0:::::::*
cisco	ios_xr	3.6.1	cpe:2.3:o:cisco:ios_xr:3.6.1:::::::*
cisco	ios_xr	3.6.2	cpe:2.3:o:cisco:ios_xr:3.6.2:::::::*
cisco	ios_xr	3.6.3	cpe:2.3:o:cisco:ios_xr:3.6.3:::::::*
cisco	ios_xr	3.7.0	cpe:2.3:o:cisco:ios_xr:3.7.0:::::::*
cisco	ios_xr	3.7.1	cpe:2.3:o:cisco:ios_xr:3.7.1:::::::*
cisco	ios_xr	3.7.2	cpe:2.3:o:cisco:ios_xr:3.7.2:::::::*
cisco	ios_xr	3.7.3	cpe:2.3:o:cisco:ios_xr:3.7.3:::::::*
cisco	ios_xr	3.8.0	cpe:2.3:o:cisco:ios_xr:3.8.0:::::::*
cisco	ios_xr	3.8.1	cpe:2.3:o:cisco:ios_xr:3.8.1:::::::*

References for CVE-2009-2055

URL	Tags
http://mailman.nanog.org/pipermail/nanog/2009-August/012719.html	Mailing List
http://securitytracker.com/id?1022739	Broken Link
http://www.cisco.com/en/US/products/products_security_advisory09186a0080af150f.shtml	Patch Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2009-2055	US Government Resource

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